THE CHINA CLAY INDUSTRY OF CORNWALL AND DEVON. 137 
as an open quarry for tin for four centuries, not only is the mica 
washed away in this manner, hut the large quantity of sand 
produced is also washed away at night, and thus very large accu- 
mulations of sand have collected in the valleys below St. Austell, 
St. Blazey, and elsewhere. 
The clay having settled in the pits to a consistency somewhat 
thicker than cream, is in old-fashioned works run out into 
shallow excavations called “ pans.” These are about two feet 
deep — the clay is put into them during the winter months, and 
is allowed to remain until nearly dry, when it is cut out in 
square blocks and piled up under sheds, or in the open air, till 
completely dry. By this mode of working a good deal of loss 
is experienced, as every block of clay is more or less injured at 
the surface by exposure for months to the vicissitudes of the 
weather, the invasions of sheep, cattle, and geese — which latter 
abound on the moors — and the mischief of stone-throwing boys. 
When thoroughly dry, therefore, every block has to be separately 
scraped before it is in a fit state to be sold. 
The scraping operation is a peculiar and somewhat ghastly 
sight to those who see it for the first time. Gangs of tall 
women, white-aproned — every vestige of complexion hidden 
with white clay — stand at tables scraping the blocks all day 
long, with a little three-cornered scraper like a miniature Dutch 
hoe, and often dismally singing hymns which sound like dirges. 
The advantage of air-drying is that no expense is incurred 
for fuel — the disadvantage is the loss incurred by scraping, the 
expense of scraping, and the large area required for the drying 
pans. 
In more modern works the air-drying is mostly replaced by 
kiln-drying. Long kilns are built of fire-clay tiles covering 
brickwork flues from 60 to 100 or even 150 feet long. The clay 
from the circular pits is first run into large tanks, where it 
remains for a month or two, till pretty stiff. It is then taken 
into the kiln or 66 dry ” on tramwaggons, and dried by throwing 
it upon the hot tiles. When dry it is cut up into convenient 
sized blocks and piled up ready for market. On the whole, the 
smaller amount of waste in kiln-dried clay, and the saving of 
expense for scraping, more than makes up for the expense of 
fuel, and few modern works are without kilns for drying. 
The preparation of the china stone for the market is a much 
more simple operation. China stone is also a kind of granite, 
which is, however, only partially decomposed, but it is only valu- 
able when it happens to be free from mica and all other minerals 
except the quartz and partially decomposed felspar. It occurs 
chiefly in the parishes of St. Stephens, St. Dennis, and Breage, 
and is often associated with china clay. The rock is simply 
quarried down, and the joints dressed over where discoloured 
